Lecture 6: Bacterial Motility + Introduction to pili/fimbriae

Question 1

What are the different types of flagella?

Answer 1

• Monotrichous
• Amphitrichous
• Lophotrichous
• Peritrichous

Question 2

Describe Monotrichous flagella

Answer 2

Just one flagella at the end of the cell

Question 3

Describe Amphitrichous flagella

Answer 3

Flagella at either end of the cell

Question 4

Describe Lophotrichous flagella

Answer 4

multiple flagella at either end of the cell

Question 5

Give an example of a bacteria that has Monotrichous flagella

Answer 5

Vibrio cholerae

Question 6

Give an example of a bacteria that has Amphitrichous flagella

Answer 6

Campylobacter jejuni

Question 7

Give an example of a bacteria that has Lophotrichous flagella

Answer 7

(Helicobacter pylori)

Question 8

Describe Peritrichous
flagella

Answer 8

Grow flagella all over the cell i.e e coli

Question 9

Give an example of a bacteria that has Peritrichous flagella

Answer 9

e coli

Question 10

What do motility patterns alternate between?

Answer 10

Run and tumble

Question 11

Describe bacterial movement (run and tumble)

Answer 11

• Run: motor rotates anti clockwise. The flagellar filaments form bundle and propel cells
• Tumble: quick reversal of motor to clockwise rotation. This produces a twisting force that transforms the flagella into a righthanded helix. The bundke falls apart rapidly
• Run: motor rotates anti-clockwise again. The flagellar filaments form a bundle and propel in a new direction.

Question 12

What are the 4 tactic responses of bacteria

Answer 12

Aerotaxis

Chemotaxis

Magnetotaxis

Phototaxis

Question 13

Describe aerotaxis

Answer 13

movement usually towards oxygen

Question 14

Describe Chemotaxis

Answer 14

movement usually towards nutrients but also away from toxins

Question 15

Dewscribe Magnetotaxis

Answer 15

movement along lines of magnetism

Question 16

Describe Phototaxis

Answer 16

movement towards light

Question 17

Explain how chemotaxis in bacteria works

Answer 17

• Transmembrane proteins called Methyl-accepting chemotaxis proteins (MCP) stick out of cells and detect and measure changes in environment
• These interact with cytoplasmic proteins called che proteins which interact with rings of motor regulating direction in which it turns (dictate of the cell runs or tumbles)

Question 18

What is another name for MCP transmembrane proteins?

Answer 18

transducer proteins

Question 19

How many different MCPs does e coli have?

Answer 19

5, which each detect different compounds

Question 20

What happens when MCP interacts with sensor kinase CheA?

Answer 20

The sensor kinase CheA autophosphorolates

Question 21

What happens when a bacteria is in the presence of an attractant?

Answer 21

The concentration of phosphorylated sensor kinase CheA decreases, anti-clockwise motion, longer runs

Question 22

What happens when a bacteria is in the presence of a repellent?

Answer 22

The concentration of phosphorylated sensor kinase CheA increases, clockwise motion, more tumbling

Question 23

What does CheA-P phosphorolate?

Answer 23

CheY

Question 24

What does CheY-P bind to ?

Answer 24

The flagellar motor

Question 25

What happens when CheY-P binds to the flagellar motor?

Answer 25

There's a change from anti-clockwise rotation to clockwise rotation, and the bacteria tumbles

Question 26

What dephosphorylates CheY-P?

Answer 26

A phosphatase, CheZ. This allows the anti-clockwise motion to resume

Question 27

How does a bacterial cell integrate the signals of attractants and repellants ?

Answer 27

By using CheR to methylate the MCP. The more methyl groups the MCP has, the less sensitive it is to the attractant and the repellent. CheB increases methylesterase activity and the demethylation of the MCP

Question 28

Low conc. attractant

Answer 28

high CheA-℗, high CheB-℗ Demethylation of MCP, increasing sensitivity to attractant (longer runs)

Question 29

High conc. attractant

Answer 29

low CheA-℗, low CheB-℗ High methylation level of MCP, decreasing sensitivity to attractant, increasing autophosphorylation of CheA (more likely to tumble)

Question 30

is it true that each MCP receptor binds different ligands and different species have different optimum niches ?

Answer 30

Yes

Question 31

What is it called when a bacteria moves without the flagella?

Answer 31

Gliding

Question 32

Which bacteria is gliding common in ?

Answer 32

cyanobacteria

Question 33

How quickly does F. johnsoniae glide?

Answer 33

at up to 10 µm/s

Question 34

Describe how F. johnsoniae glides

Answer 34

Latex spheres added to F. johnsoniae bind to and are rapidly propelled along cells Suggests that adhesive molecules move laterally along the cell surface during gliding

Question 35

What are the genes associated with gliding?

Answer 35

gld genes

Question 36

What happens if you disrupt gld genes?

Answer 36

- You get a loss of motility - increases resistance to bacteriophages that infect wild-type cells - loss of the ability to digest the insoluble polysaccharide chitin

Question 37

Describe twitching motility via type IV pilus

Answer 37

- Based on type IV pili first extending from cell surface then being retracted, dragging cell along surface - Powered by ATP hydrolysis - Retraction proteins control direction of movement

Question 38

Which bacteria can gas vesicles be found in?

Answer 38

In planktonic bacteria (e.g. cyanobacteria), and some archaea

Question 39

What are gas vesicles?

Answer 39

Protein vesicles that contain gas, which confers buoyancy to the cell

Question 40

Describe how gas vesicles work

Answer 40

Allow cells to float up to oxygenated water or towards the light Can be involved in vertical migration in aquatic systems such as lakes

Question 41

What are fimbriae/pili?

Answer 41

Surface appendages, multi-subunit proteins

Question 42

What do fimbriae/pili do?

Answer 42

Allows for adhesion to other bacteria, host cells or environmental surfaces

Question 43

What are specialied pili associated with?

Answer 43

genetic exchange between bacteria

Question 44

How do some researchers distinguish between fimbriae and pili?

Answer 44

by linking pili to conjugation and gene exchange, but this is not always true

Question 45

What tests have defined at least 7 groups of pili?

Answer 45

Traditional agglutination tests

Question 46

What do agglutination tests use?

Answer 46

use yeasts, red blood cells, or tissue culture cells with or without mannose inhibition

Question 47

What are the most important pili?

Answer 47

type I and type IV

Question 48

Are fimbiae and pili major determinants of bacterial virulence?

Answer 48

Yes, they allow pathogens to attach to (colonise) tissues

Question 49

Is it true that fimbiae and pili sometimes aid resistance to immune cell phagocytosis?

Answer 49

Yes

Question 50

Because fimbriae are antigenic, what are there antigens called?

Answer 50

Colonisation Factor Antigens (CFA)

Question 51

What antibodies detect the fimbriae/pilli and block bacterial colonisation?

Answer 51

Secretory antibodies (IgA)

Question 52

What antibodies detect the fimbriae/pilli and catalyse phagocytosis?

Answer 52

Circulating antibodies (IgG or IgM)

Question 53

Role of fimbirae/pili in adhesion

Answer 53

- Loose association of microbe with mucus - Pili and fimbriae allow microbe cell to stick to the surface of the epithelial cell. Tip protein binds to glycolopid receptors on epithelial cell. - Pili pulls microbe cloe to the host cell - Microbe becomes invasive (into or through submucosal epithelial cells ) -